1. Field of the Invention
The present invention relates to a transmission method of notice data indicating that event data to be transmitted corresponding to an occurrence of the event has been transmitted.
2. Description of the Related Art
As a packet loss determination method of a periodic packet (e.g., video data packet) that is periodically transmitted, a method is known for checking a sequence number applied to the packet. A reception apparatus can detect a packet loss by finding a loss of the sequence number.
On the other hand, Japanese Patent Application Laid-Open No. 2005-328131 discusses a method for determining a packet loss of an event packet transmitted corresponding to an occurrence of an event. In Japanese Patent Application Laid-Open No. 2005-328131, a transmission apparatus applies different marker bits to a leading packet and an ending packet of a packet group corresponding to subtitles that are irregularly transmitted.
The reception apparatus determines that the ending packet is lost when the ending packet is not received within a predetermined time since the leading packet has been received. However, with respect to some event data, it takes time to detect the loss of the event data.
An example of an aforementioned case includes a case where the number of packets of the event data to be transmitted is changed corresponding to the occurring event. Particularly, when the event having the small number of packets of the event data to be transmitted occurs, a predicted time since the leading packet has been received until the ending packet is received is longer than an actual time. Accordingly, when the predicted time has elapsed, a longer than actual time for detecting the loss of the ending packet has elapsed.
Further, when one packet of the event data is transmitted according to the occurrence of the event, the different marker bits cannot be applied to the leading packet and the ending packet. Thus, until the packet of the next event data is received, the packet loss of the event data may not be detected.